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A Short Course in Basic Meteorology

A Short Course in Basic Meteorology. PART 1. Pierre Bourgouin, Dov Bensimon, René Servranckx Environment Canada – Canadian Meteorological Centre – Emergency Response Section Developed by: Julie Dion. Outline. Day 1 – Basic meteorology What is the atmosphere? (1/2 h – chap. 1)

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A Short Course in Basic Meteorology

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  1. A Short Course in Basic Meteorology PART 1 Pierre Bourgouin, Dov Bensimon, René Servranckx Environment Canada – Canadian Meteorological Centre – Emergency Response Section Developed by: Julie Dion

  2. Outline • Day 1 – Basic meteorology • What is the atmosphere? (1/2 h – chap. 1) • What fuels it? (1/2 h – chap. 2) • How does it move? (2 h – chap. 3 and 4) • How do we observe it? (1 h – chap. 5) • How does it produce weather (1 h – chap. 6) • Day 2 – Basic meteorology (cont’d) • How does it produce weather (1 h – chap. 7) • Day 2 – Dispersion and meteorological models

  3. Chapter 1 The Atmosphere

  4. What is the atmosphere? It is a heat engine… like the drinking bird! It transforms thermal energy (heat) Into mechanical work (wind)

  5. What is the atmosphere? It is a blanket made of different gases Traces of: Main elements: • Nitrogen (78%) • Oxygen (21%) • Argon (1%) • Water vapour • Carbon dioxide • Neon • Helium • Krypton • Hydrogen • Ozone Also: Small solidparticles

  6. What is the atmosphere? It is a layered blanket • Troposphere (0 to 10 km) • Stratosphere (10 to 50 km) • Mesosphere (50 to 80 km) • Thermosphere (80 to 100 km)

  7. What is the atmosphere? More layers…

  8. Chapter 2 Heating the Atmosphere

  9. What fuels the atmosphere? • Huge nuclear reactor • Emits short energetic radiation • from ultraviolet (0.12 µm) • to near infrared (4 µm) • including visible (0.34-0.7 µm)

  10. What fuels the atmosphere? • Radiation is not heat • It needs to be absorbed

  11. What fuels the atmosphere? Annual mean global energy budget for the earth-atmosphere system

  12. Chapter 3 Atmospheric Pressure and Air Circulation

  13. How does the atmosphere move? PRESSURE Atmospheric pressure: The weight of a column of air above a certain level It is expressed in: millibar = mb hectoPascal = hPa

  14. How does the atmosphere move? Hydrostatic equation: As height goes UP Pressure goes DOWN gandRare constants p and T cancel somewhat

  15. How does the atmosphere move? Hypsometric equation Vertical pressure distribution

  16. How does the atmosphere move? Resulting horizontal pressure distribution

  17. How does the atmosphere move? Coriolis effect

  18. How does the atmosphere move?

  19. How does the atmosphere move?

  20. How does the atmosphere move? Ekman spiral Free atmosphere Planetary boundary layer

  21. How does the atmosphere move? Local effects

  22. How does the atmosphere move? Thermal wind Therefore, in the horizontal: • Pressure decreases with height • Rate of decrease is greater in cold air Wind speed aloft = surface wind speed + thermal wind speed Wind direction aloft = surface wind direction + thermal wind direction

  23. Exercise 1 Pressure and Wind

  24. Chapter 4 The General Circulation

  25. How does the atmosphere move? Planetary waves (aloft) Zonal Meridional

  26. How is the energy transferred? Energy hierarchy and cascade 2nd Law of thermodynamics: Any system must tend toward a state of randomness (maximum entropy). Big whirls have little whirls which feed on their velocity. Little whirls have lesser whirls, and so on to viscosity. L. Richardson

  27. How is the energy transferred? General circulation

  28. How is the energy transferred? Planetary waves (aloft) Zonal Meridional

  29. How is the energy transferred? Jet stream • Narrow stream of air • Rapidly flowing • Embedded in main flow • Thousands of kilometres long • A few hundred kilometres wide • At least 60 knots (110 km/h) Cause: Horizontal temperature gradient through a thick layer

  30. How is the energy transferred? Global water budget Precipitation Evaporation Water vapour Water vapour

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